The present disclosure relates to harvesting combines that use rotary threshing of severed crop and more particularly to controlling the rate of crop flowing through the rotary threshing system and, consequently, threshing aggression, separation efficiency, and power consumption.
In a grain harvesting machine that uses the rotary type of threshing and separating process where the crop enters one end of the rotor encasement (cage) and is turned around and around in that cage by the spinning rotor with threshing element protrusions on its outer skin, it is normal to have long, blade like protrusions on the inner circumference of the cage in select locations. These protrusions engage the spinning crop and force it to move rearwardly in the cage along these blades (called guide vanes, or simply vanes). In a rotor cage that is essentially round or oval in shape, this requires that the vanes be designed with a radius of curvature that corresponds to the curvature of the cage at the place and orientation where the vane is attached to the cage. It is currently typical and exclusive that these vanes occur only in areas that are not part of the concave and grate components of the cage, and are limited to the non-removable upper portions of the cage.
In some cases, the vanes are permanently attached to the cage, often at the top of the cage on components known as top covers and, as such, can only have one effect on the crop flow—to accelerate or retard rearward progression of the crop material along the vane's angle of inclination. In other cases the vanes can be located on the sides of the cage (typically above the vertical midpoint of the cage circle) and bolted to (through) the cage wall in a system of slots that allow the pitch angle of the vanes to be altered. This adjustability of the vanes gives the operator of the machine the option to change the pitch of the vanes in order to either retard or accelerate the movement of crop through the rotary thresher. This adjustability is accomplished by means of wrenches and pry bars, at some significant human distress given that there are significant quantities of irritating crop dust present. The changing process often is the deterrent to making such changes, even though the operator knows the change would improve performance.
Secondly, and not insignificantly, the shape of the vane (when it is standing more perpendicular to the flow) is significantly different than when it is laying back and less perpendicular to the direction of crop flow. This necessarily requires that the vane physically deform within the elastic range of the steel in the vanes, leads to significant resistance to changing of the vane angle, and requires numerous very tight bolts to maintain the deformation up against the inner wall of the cage. The gripping force required to keep the vanes at the proper angle actually precludes any kind of movement without loosening the bolts and precludes any type of actuator moving the vanes in concert by some powered mechanical means. Therefor, most needed vane angle adjustments simply are not implemented even though the needed angle(s) of the vanes changes routinely with crop type and crop condition. To the operator, it is “just not worth getting dirty and skinning knuckles!”; even though the adjustment could result in a profound improvement in machine productivity.
To date, any attempt to remotely control these vane angles (given the change in ovality of the vane versus cage) has amounted to simply “wagging” the tail of a few of the vanes in that the cantilevered and hinged short section on the trailing end of the vane is allowed to change the angle of an insignificant length of a chosen few vanes. Change in performance is not significant, and the feature is largely face value versus functionality.